The butterfly's head is the location of its feeding and sensory structures. The almost spherical head contains its brain, two compound eyes, its proboscis, pharynx (the start of the digestive system), the point of attachment of its two antennae, Johnston's organ, mustache-like sensory palps, etc.

Butterflies have no jaws; they sip liquid food through the proboscis, which uncoils for feeding. The proboscis is a a tube-like, flexible "tongue" that butterflies and moths use to sip their liquid food (usually flower nectar or the liquid from rotting fruits). The proboscis uncoils to sip food, and coils up again into a spiral when not in use. The lepidopteran with the longest proboscis is the hawk moth.

Compound eyes are made up of many hexagonal lens/corneas which focus light from each part of the insect's field of view onto a rhabdome (the equivalent of our retina). An optic nerve then carries this information to the insect's brain. Butterflies and moths see very differently from us; they can see ultraviolet rays (which are invisible to us).

Antennae (singular antenna) are sensory appendages attached to the head of butterflies and moths. Antennae are used for the sense of smell and balance. Butterflies have two segmented antennae with a small club at the end of each. Moths have antennae without the club.

Johnston's organ is an organ located at the base of a butterfly's antennae. This organ are responsible for maintaining the butterfly's sense of balance and orientation, especially during flight.

Palps are the mustache-like scaly mouthparts of adult butterflies that are on each side of the proboscis. These palps are covered with sensory hairs and scales, and test whether something is food or not.